Ability to remotely monitor atrial high-rate episodes using a single-chamber implantable cardioverter-defibrillator with a floating atrial sensing dipole.

AIMS: To allow timely initiation of anticoagulation therapy for the prevention of stroke, the European guidelines on atrial fibrillation (AF) recommend remote monitoring (RM) of device-detected atrial high-rate episodes (AHREs) and progression of arrhythmia duration along pre-specified strata (6 min…<1 h, 1 h…<24 h, ≥ 24 h). We used the MATRIX registry data to assess the capability of a single-lead implantable cardioverter-defibrillator (ICD) with atrial sensing dipole (DX ICD system) to follow this recommendation in patients with standard indication for single-chamber ICD. METHODS AND RESULTS: In 1841 DX ICD patients with daily automatic RM transmissions, electrograms of first device-detected AHREs per patient in each duration stratum were adjudicated, and the corresponding positive predictive values (PPVs) for the detections to be true atrial arrhythmia were calculated. Moreover, the incidence and progression of new-onset AF was assessed in 1451 patients with no AF history. A total of 610 AHREs ≥6 min were adjudicated. The PPV was 95.1% (271 of 285) for episodes 6min…<1 h, 99.6% (253/254) for episodes 1 h…<24 h, 100% (71/71) for episodes ≥24 h, or 97.5% for all episodes (595/610). The incidence of new-onset AF was 8.2% (119/1451), and in 31.1% of them (37/119), new-onset AF progressed to a higher duration stratum. Nearly 80% of new-onset AF patients had high CHA2DS2-VASc stroke risk, and 70% were not on anticoagulation therapy. Age was the only significant predictor of new-onset AF. CONCLUSION: A 99.7% detection accuracy for AHRE ≥1 h in patients with DX ICD systems in combination with daily RM allows a reliable guideline-recommended screening for subclinical AF and monitoring of AF-duration progression.

Functional response to cardiac resynchronization therapy in patients with renal dysfunction and subsequent long-term mortality.

INTRODUCTION: Renal dysfunction is associated with increased morbi-mortality in heart failure patients. Data regarding functional and clinical efficacy of cardiac resynchronization therapy (CRT) in this population are limited. METHODS AND RESULTS: We aimed to evaluate the rate of functional response to CRT in patients with renal dysfunction and its association with long-term mortality. Our study included a total of 179 consecutive patients implanted between 2007 and 2010. The rate of functional response to CRT (defined by a composite score using New York Heart Association functional class, 6-minute walk test, and quality of life) was compared between patients with and without renal dysfunction (defined as eGFR < or ≥60 mL/min/1.73 m(2) ). Survival analysis estimates were constructed according to the Kaplan-Meier method, with results comparison using the log-rank test. During a median follow-up of 4.2 years, 73 patients (40%) died. Patients with low eGFR were older (72 ± 8 years vs. 64 ± 12 years; P < 0.001), and had higher prevalence of ischemic heart disease (75% vs. 53%; P = 0.003). Functional response rates did not differ significantly between patients with and without renal dysfunction (58% and 69%, respectively; P = 0.14). Despite overall higher mortality in patients with low eGFR (53.8% vs. 22.7%; P < 0.001), the presence of functional response at 1 year among patients with renal dysfunction was still independently associated with an improved long-term survival (HR = 0.49 [95%CI: 0.28-0.83]; P = 0.009). CONCLUSION: Functional response to CRT at 1 year does not differ significantly between patients with or without kidney disease, and is an independent predictor of improved long-term survival in patients with renal dysfunction.

Safety and efficacy of strategic implantable cardioverter-defibrillator programming to reduce the shock delivery burden in a primary prevention patient population.

AIMS: Strategically chosen ventricular tachycardia (VT)/ventricular fibrillation (VF) detection and therapy parameters aimed at reducing shock deliveries were proven effective in studies that utilized single manufacturer devices with a follow-up of up to 1 year. Whether these beneficiary effects can be generalized to additional manufacturers and be maintained for longer periods is to be determined. Our aim was to evaluate the durability and applicability of the programming of strategic implantable cardioverter-defibrillators (ICDs) of various manufacturers, which is aimed at reducing the shock delivery burden in primary prevention ICD recipients. METHODS AND RESULTS: A retrospective analysis of prospectively collected data of 300 ICD recipients of various manufacturers was conducted; 160 devices were strategically programmed to reduce shocks and 140 were not. The primary endpoint was the composite of death and appropriate shocks. Additional outcomes were inappropriate shocks, syncope events, and non-sustained VTs. At a median follow-up of 24 months, 19 patients died, 31 received appropriate shocks, and 41 received inappropriate shocks. Multivariate analysis showed that strategic programming dedicated to shock reduction was associated with a 64% risk reduction in the primary endpoint [hazard ratio (HR): 0.13-0.93; P = 0.03] and a 70% reduction in inappropriate shock deliveries (HR: 0.16-0.72; P = 0.01). Very few syncope events occurred (five patients, 1.6%), and there was no between-group difference in this outcome. CONCLUSION: Utilization of strategically chosen VT/VF detection and therapy parameters was found to be effective and safe in ICDs of various manufacturers at a median follow-up period of 2 years among primary prevention patients.

LQT5 masquerading as LQT2: a dominant negative effect of KCNE1-D85N rare polymorphism on KCNH2 current.

AIMS: KCNE1 encodes an auxiliary subunit of cardiac potassium channels. Loss-of-function variations in this gene have been associated with the LQT5 form of the long QT syndrome (LQTS), secondary to reduction of I(Ks) current. We present a case in which a D85N rare polymorphism in KCNE1 is associated with an LQT2 phenotype. METHODS AND RESULTS: An 11-year old competitive athlete presented with mild bradycardia and a QTc interval of 470 ms. An LQT2 phenotype, consisting of low-voltage bifid T waves, was evident in the right precordial electrocardiogram leads. During the tachycardia phase following adenosine, QTc increased to 620 ms. Genetic analysis revealed a rare heterozygous polymorphism in KCNE1 predicting the substitution of asparagine for aspartic acid at position 85 of minK (D85N). Patch clamp experiments showed that KCNE1-D85N, when co-expressed with KCNH2 in TSA201 cells, significantly reduced I(Kr). Homozygous co-expression of the mutant with KCNH2 reduced I(Kr) tail current by 85%, whereas heterozygous co-expression reduced the current by 52%, demonstrating for the first time a dominant-negative effect of D85N to reduce I(Kr). Co-expression of the mutant with KCNQ1, either homozygously or heterozygously, produced no change in I(Ks). CONCLUSIONS: Our results suggest that a rare polymorphism KCNE1-D85N underlies the development of an LQT2 phenotype in this young athlete by interacting with KCNH2 to cause a dominant-negative effect to reduce I(Kr). Our data provide further evidence in support of the promiscuity of potassium channel ß subunits in modulating the function of multiple potassium channels leading to a diversity of clinical phenotypes.

The effects of anodal stimulation on electrocardiogram, left ventricular dyssynchrony, and acute haemodynamics in patients with biventricular pacemakers.

AIMS: Anodal stimulation (ANS) is a recognized phenomenon among patients with cardiac resynchronization therapy (CRT); this is noted during left ventricular (LV) pacing by the LV tip to right ventricular (RV) ring configuration. Its incidence varies according to the implanted hardware. We aim at evaluating the incidence of ANS and its acute haemodynamic effects among CRT patients. METHODS AND RESULTS: We screened all our patients who previously had an implanted CRT-P/D devices for ANS. After excluding all non-eligible devices, the initial screening was done by evaluating the programmer electrocardiogram (ECG) during device interrogation while pacing LV only from LV tip to RV ring. Those with ANS underwent screening by 12-lead ECG during biventricular pacing with VV interval programmed to 0. Patients with electrocardiographic evidence of ANS underwent detailed echocardiography. We screened 224 patients, 187 patients were excluded due to various causes. Thirty-seven subjects were analysed for this study. Anodal stimulation was found in 29 patients (78.4%) by primary screening. Twelve patients (41.4%) showed electrocardiographic evidence of ANS by 12-lead ECG. The ANS threshold was significantly higher than true bipolar LV threshold (4.5±1.7 vs. 1.1±0.3 V, respectively, P=<0.0001). Ten patients, with ECG evidence of ANS, underwent detailed echocardiography during biventricular pacing with and without ANS. Overall, there were no significant differences in the haemodynamic, echocardiographic, or resynchronization effects with and without ANS, two patients showed significant reduction in LV function with ANS. CONCLUSION: Anodal stimulation is a common phenomenon among CRT patients. In many cases ANS is seen with LV pacing only, while these changes may not be seen by ECG during biventricular pacing. Echocardiography did not show any significant acute haemodynamic benefit during ANS, and some patients may even deteriorate.

Qual a contribuição do tilt training (treinamento postural) na prevenção da síncope vasovagal ? / Tilt training: does it have a role in preventing vasovagal syncope? / ¿Cuál es el aporte del tilt training (entrenamiento postural) a la prevención del síncope vasovagal?

Histórico: A síncope vasovagal é um dos quadros clínicos mais comuns em adultos jovens. Estudos anteriores demonstram a eficácia do tilt training (treinamento postural) no tratamento desse transtorno clínico. Realizou-se um estudo prospectivo e randomizado com o objetivo de avaliar a contribuição do tilt training no tratamento de adultos jovens acometidos pela síncope vasovagal. Métodos: Quarenta e seis soldados , 25 dos quais do sexo masculino, média de idade de 19,4 mais ou menos 0,8 anos e diagnóstico clínico de síncope vasovagal pelo tilt teste, foram divididos aleatoriamente em dois grupos: um grupo controle e outro acometido de tilt training diariamente, por três meses. Nos dois grupos, os participantes foram instruídos a aumentar a ingestão de líquidos e sal e evitar situações indutoras de síncope, tais como permanecer em pé por períodos longos. Resultados: A adesão ao programa de treinamento, caracterizada pela realização de 50 por cento ou mais das sessões diárias de tilt training, foi de 91 por cento durante o primeiro mês, caindo para 58 por cento nos três meses. Os que realizaram o treinamento apresentaram uma média (distância interquartilica) e 5,0 episódios de síncope (0,5 a 16,0) durante um ano de acompanhamento, enquanto o grupo controle apresentou média de 2,0 episódios (0 a 6,0, P igual 0,737). Após a randomização não houve diferença significativa no tempo de ocorrência do primeiro episódio entre os dois grupos: média de 1,0 por mês (0,5 a 2,0) no grupo em tratamento...

Background: Vasovagal syncope is one of the most common medical conditions in young adults. Previous trials have shown effectiveness of tilt training in treating this condition. We conducted a prospective, randomized study in order to evaluate the role of tilt-training in young adults with vasovagal syncope. Methods: Forty-six soldiers (mean age 19.4 ± 0.8 years, 25 males), with a clinical diagnosis of vasovagal syncope supported by positive tilt test, were randomized to either three months of daily tilt training (treatment group), or no training (control group). Patients in both groups were instructed to increase fluid and salt intake, and to refrain from syncope-inducing situations, such as prolonged standing. Results: Compliance, defined as performing 50% or more of the tilt training daily sessions, was 91% during the first month, and declined to 58% during three months. Treatment group patients had a median (interquartile range) of 5.0 (0.5–16.0) syncope episodes during one-year follow up, compared to a median of 2.0 (0–6.0) episodes in the control group (P = 0.737). Also, there was no difference in time to first syncope after randomization between groups: a median of 1.0 (0.5–2.0) month in the treatment group, compared to 0.8 (0.5–2.0) month in the control group (P = 0.336). Conclusions: Adding daily three-month tilt training to modifications in lifestyle does not improve treatment results in youngadults with vasovagal syncope. Good compliance is difficult to achieve in a tilt training program.

Historial: El síncope vasovagal es uno de los cuadros clínicos más comunes en adultos jóvenes. Estudios anteriores han demostrado la eficiencia del tilt training (entrenamiento postural) en el tratamiento de ese trastorno clínico. Se llevó a cabo un estudio prospectivo y randomizado con el objetivo de evaluar el aporte del tilt training al tratamiento de adultos jóvenes acometidos por el síncope vasovagal. Métodos: Cuarenta y seis soldados, 25 de ellos del sexo masculino, promedio de edad de 19,4 ± 0,8 años y diagnóstico clínico de síncope vasovagal por el tilt test, fueron divididos aleatoriamente en dos grupos: un grupo control y otro sometido a tilt training diariamente, por tres meses. En ambos grupos, los participantes fueron instruidos a aumentar la ingesta de líquidos y sal y evitar situaciones inductoras del síncope, tales como permanecer en pie por largos períodos. Resultados: La adhesión al programa de entrenamiento, caracterizada por la realización del 50% o más de las sesiones diarias de tilt training, fue del 91% durante el primer mes, bajando al 58% a los tres meses. Quienes llevaron a cabo el entrenamiento presentaron un promedio (distancia intercuartílica) de 5,0 episodios de síncope (0,5 a 16,0) durante un año de acompañamiento, mientras el grupo control presentó un promedio de 2,0 episodios (0 a 6,0; P = 0,737). Tras la randomización, no hubo diferencia significativa en el tiempo de ocurrencia del primer episodio de síncope entre ambos grupos: promedio de 1,0 por mes (0,5 a 2,0) en el grupo en tratamiento y 0,8 (0,5 a 2,0) en el grupo control (P = 0,336). Conclusiones: La realización diaria del tilt training, aliada a los cambios de estilo de vida, no produjo mejora en el resultado del tratamiento de adultos jóvenes con síncope vasovagal. Se verificó asimismo la dificultad de obtener buena adhesión al programa de entrenamiento postural.

Comparison of results with different left ventricular pacing leads.

AIMS: To compare different coronary sinus (CS) leads and delivery systems (DSs) for left ventricular pacing. METHODS AND RESULTS: Delivery systems-related (including CS dissection and dislocations during sheath/stylet removal) and lead-related (including failure to accomplish implantations and long-term malfunctions resulting in abandonment or repositioning/replacing of the lead) complications between systems and leads were compared. We used Medtronic (MDT) attain DS (n = 123) with over-the-wire (OTW) (4193, 4194) and stylet-driven (2187) leads, and Guidant (GDT) DS (n = 126) with Easytrak OTW leads (4513, 4518, and 4525). Coronory sinus dissection occurred in 6/123 (5%) cases using the MDT DS vs. 7/126 (6%) with GDT DS (P= NS). Dislocations during sheath/stylet removal occurred in 8/123 cases (6%) with MDT DS, and in 8/126 (6%) with GDT DS (P= NS). Failure to achieve successful implantation occurred in 6/32 (19%) of the 2187 leads, in 11/87(13%) of the 4193/4194 leads, in 7/94(7%) of the 4513/4518 leads, and in 4/29 (14%) of the 4525 leads (P= NS). Long-term lead-related complications occurred in 5/32 (15%) of the 2187 leads, 19/80 (23%) of the 4193/4194 leads, 19/93 (20%) of the 4513/4518 leads, and 2/28 (7%) of the 4525 leads (P= NS). CONCLUSION: No significant differences in complication rates between systems and leads were observed.

Tilt training: does it have a role in preventing vasovagal syncope?

BACKGROUND: Vasovagal syncope is one of the most common medical conditions in young adults. Previous trials have shown effectiveness of tilt training in treating this condition. We conducted a prospective, randomized study in order to evaluate the role of tilt-training in young adults with vasovagal syncope. METHODS: Forty-six soldiers (mean age 19.4 +/- 0.8 years, 25 males), with a clinical diagnosis of vasovagal syncope supported by positive tilt test, were randomized to either three months of daily tilt training (treatment group), or no training (control group). Patients in both groups were instructed to increase fluid and salt intake, and to refrain from syncope-inducing situations, such as prolonged standing. RESULTS: Compliance, defined as performing 50% or more of the tilt training daily sessions, was 91% during the first month, and declined to 58% during three months. Treatment group patients had a median (interquartile range) of 5.0 (0.5-16.0) syncope episodes during one-year follow up, compared to a median of 2.0 (0-6.0) episodes in the control group (P = 0.737). Also, there was no difference in time to first syncope after randomization between groups: a median of 1.0 (0.5-2.0) month in the treatment group, compared to 0.8 (0.5-2.0) month in the control group (P = 0.336). CONCLUSIONS: Adding daily three-month tilt training to modifications in lifestyle does not improve treatment results in young adults with vasovagal syncope. Good compliance is difficult to achieve in a tilt training program.

Randomized comparison of J-shaped atrial leads with and without active fixation mechanism.

BACKGROUND: In this prospective, randomized, controlled study, we compared the performance of J-shaped active fixation (AF) atrial leads with J-shaped passive fixation (PF) leads, over a 1-year follow-up period. METHODS: A total of 200 consecutive patients were prospectively randomized for implantation with a Medtronic 5568 AF lead model (n = 103; Minneapolis, MN, USA) versus a Medtronic 5592 PF model (n = 97), and all lead-related measurements and complications were recorded over one year. RESULTS: All leads were successfully implanted with a nonsignificant difference in crossover rate to the alternative lead due to failed implantation (1 in the AF and 4 in the PF group, P = NS). Fluoroscopy time during implantation procedure was significantly shorter in the PF group (2.1 +/- 3.6 vs 3.3 +/- 4.5 minute, P < 0.05). Pacing thresholds during implantation were significantly lower in patients with PF leads (0.7 +/- 0.3 V vs 0.9 +/- 0.3 V, P < 0.001) and this difference persisted at 1-year follow-up (0.8 +/- 0.6 V vs 1.3 +/- 0.9 V in PF and AF leads respectively, P < 0.05). Lead-related complications occurred in PF and AF with similar frequency (4% and 9% respectively, P = 0.2). However, pericardial complications occurred only in the AF group (6 cases, P = 0.01). Lead dislodgement was observed in only two cases-both in the PF group (P = 0.3). CONCLUSION: Both types of J-shaped atrial leads had reasonable performance. PF leads required shorter fluoroscopy time for implantation, demonstrated a better pacing threshold over a 1-year follow-up period and had no pericardial complications, while AF lead implantation was complicated by pericardial irritation and/or effusion in 6% cases (P = 0.01).

Improvement of congestive heart failure by upgrading of conventional to resynchronization pacemakers.

AIMS: To compare the clinical response of patients with right ventricular apical pacing (RVAP) upgraded to cardiac resynchronization therapy (CRT) to that of previously nonpaced heart failure (HF) patients who had de novo CRT implantation. BACKGROUND: The role of CRT in patients with wide QRS and HF due to RVAP is less well established than in other CRT candidates. METHODS: Ninety-eight consecutive patients with CRT were studied (mean age 70, mean ejection fraction 0.23). Group A: patients having RVAP prior to CRT implantation (n = 25), group B: patients without prior RVAP (n = 73). Clinical and echocardiographic parameters were recorded prior to, and 3 months after, CRT implantation. RESULTS: Group A patients had a wider QRS at baseline compared to group B (203 +/- 32 ms vs 163 +/- 30 ms respectively, P < 0.001), and a shorter 6-minute walking distance (222 +/- 118 m vs 362 +/- 119 m, respectively, P < 0.005). Otherwise, clinical and echocardiographic parameters were not different. At follow up, group A patients had an average 0.7 +/- 0.5 decrease in their NYHA functional class, compared to 0.3 +/- 0.7 in group B patients (P < 0.05). Six-minute walking distance increased by 93 +/- 113 m in group A, versus 36 +/- 120 m in group B (P = 0.22). There was no difference in echocardiographic response to CRT between the groups. CONCLUSIONS: HF patients with prior RVAP demonstrate clinical improvement after upgrading to CRT that is comparable, and in some aspects, even better than that observed in HF patients with native conduction delay who undergo de novo CRT implantation.

Mechanism of diastolic mitral regurgitation in candidates for cardiac resynchronization therapy.

It was hypothesized that restricted diastolic leaflet motion is implicated not only in the mechanism of systolic mitral regurgitation (MR) but also in the mechanism of diastolic MR observed in patients with severe heart failure. Cardiac resynchronization therapy (CRT) can oppose increased mitral leaflet tethering by increasing transmitral pressure, thereby providing an opportunity to explore this hypothesis. A total of 26 consecutive candidates for CRT with diastolic MR were compared with 26 candidates without diastolic MR. Maximal diastolic mitral leaflet opening and inflow direction and measures of mitral valve apparatus (i.e., mitral annular diameters, calculated mitral annular area, and tethering distance) were assessed from the apical 4-chamber view before and during CRT. There were no significant differences in New York Heart Association functional class, ejection fraction, QRS duration, PR interval, systolic MR grade, or 2-dimensional geometry of the mitral valve apparatus between the groups. Patients with diastolic MR had more restricted maximal diastolic leaflet openings (54 degrees +/- 17 degrees vs 71 degrees +/- 11 degrees , p = 0.003) and substantially smaller inflow angles (66 degrees +/- 7 degrees vs 79 degrees +/- 9 degrees , p = 0.0003) compared with patients without diastolic MR. After the institution of CRT, diastolic MR was eliminated in all patients, although there were no significant changes in any of the parameters of mitral valve apparatus. In conclusion, abnormal mitral valve tethering is a constitutive element of the mechanism of diastolic MR in patients with left ventricular dysfunction. Its acute resolution after CRT does not seem to be caused by changes in mitral valve geometry but rather by an increase in transmitral closing forces.

Clinical surveillance of a tined, bipolar, silicone-insulated ventricular pacing lead.

AIMS: This study assesses short- and long-term performance of the S80TB ventricular lead manufactured by Sorin Biomedica, Italy. METHODS AND RESULTS: Three hundred and thirty leads were implanted and had complete follow-up with us for a minimum of 60 months or up to failure, removal, and/or patient death (mean 40 months, range: 1 day to 81 months). Thirty-two patients (9.6%) had spontaneous lead-related complications: 7 (2.1%) occurred during the first week; 25 (7.6%) had chronic complications, of which 20 (6.1%) necessitated re-operations; 3 (0.9%) were lead material failures. Of the 110 re-operations (90 pacemaker replacements and 20 operations due to complications), 7 additional cases (6.4%) were complicated by unique connector damage that occurred during disconnection of the lead from the connector block. The Kaplan-Meier estimated 5-year lead survival free of lead material failure and free of any significant lead complication were 97.9 and 87%, respectively. CONCLUSION: The S80TB lead demonstrates an acceptable rate of acute and chronic spontaneous complications and very few lead material failures over 5 years of follow-up. However, there seems to be a relatively high incidence of connector damage during disconnection from the connector block. Extra caution is required during those procedures in patients with this lead.

Long-term performance of screw-in atrial pacing leads: a randomized comparison of J-shaped and straight leads.

OBJECTIVE: In this prospective, randomized, control study we compared performance of J-shaped (JL) and straight atrial leads (SL) with active (screw-in) fixation mechanism, over a 5-year follow-up period. SUBJECTS AND METHODS: A total of 208 consecutive patients were randomized for implantation with a Medtronic 4568 JL model (n = 103) versus a Medtronic 4068 SL model (n = 105), and all lead-related measurements and complications were recorded. RESULTS: Lead-related complications occurred in JL and SL with similar frequency (6% and 9%, respectively, P = 0.45). Lead dislodgment occurred in 8 (7.8%) cases in SL versus none in JL (P = 0.004). Lead malfunction and excessive pacing thresholds without macrodislodgment occurred more frequently in JL (11; 10.7%) than in SL (4; 3.8%), P = 0.055. Lead material failure (insulation break) occurred only once in SL at the 5-year checkup. Most complications occurred during the first year after implantation. Other events occurred in both leads with similar frequency and included: death in 39 and 35, loss of follow-up in 8 and 6, and development of atrial fibrillation in 9 and 15 patients, respectively. Of those who completed follow-up, lead impedance and pacing threshold increased significantly in both groups. P wave decreased in SL but not in JL. CONCLUSION: More dislocations occurred in SL, but were counterbalanced by more lead malfunctions and excessive pacing thresholds in the JL group. Both leads demonstrated minor deterioration in electrical measurements during follow-up, with only 1 case of lead material failure in SL. Overall, both groups demonstrated favorable lead performance throughout follow-up.

Programmable multiple pacing configurations help to overcome high left ventricular pacing thresholds and avoid phrenic nerve stimulation.

BACKGROUND: High left ventricular pacing (LVP) thresholds and phrenic nerve stimulation (PNS) are common problems with cardiac resynchronization (CRT). Newer systems capable of multiple LVP configurations may help overcome these problems without the need for reoperation. METHODS: CRT systems capable of multiple LVP configurations (Guidant models H155 and H145) were implanted in 43 patients (study group). An additional 49 patients (control group) received CRT systems (Guidant, Medtronic, Biotronik, St. Jude Medical, various models) lacking this feature. RESULTS: Overall, acute high (> or =2.5 V/0.5 ms) LVP thresholds were encountered in 13 (30%) of the study group, and 25 (50%) of control group patients (P = 0.03). PNS was encountered in 5 (12%) of the study group and 12 (24%) of control group patients (P = 0.13). All cases of high LVP thresholds and PNS in the study group were managed by switching to a different LVP configuration, while high thresholds remained in control group patients, and PNS was managed by replacing the lead. The CS lead was successfully placed in a lateral branch in 95% of study group, compared to only 77% of control group patients (P = 0.004). CONCLUSIONS: Multiple LVP configurations were clinically useful in a significant number of patients undergoing CRT system implantation by helping to overcome high LVP thresholds and PNS, and by providing more flexibility in placing the LV lead.

Pericarditis following permanent pacemaker insertion.

BACKGROUND: The appearance of pericarditis following insertion of a permanent pacemaker is not widely acknowledged in the literature. OBJECTIVES: To describe our experience with pericarditis following 395 permanent pacemaker implantations over 2 years. METHODS: We retrospectively reviewed the medical records of 395 consecutive patients in whom new pacing systems or pacemaker leads had been implanted over a 2 year period. We searched the records for pericarditis that developed within 1 month after pacemaker implantation according to the ICD-9 code. The incidence, clinical picture, response to treatment, and relationship to lead design and location were studied. RESULTS: Eight cases (2%) of pericarditis following implantation were detected. Clinical manifestations in all patients were similar to those of post-pericardiotomy syndrome and included chest pain (n = 7), friction rub (n = 1), fever (n = 2), fatigue (n = 2), pleural effusion (n = 2), new atrial fibrillation (n = 2), elevated erythrocyte sedimentation rate (n = 4), and echcardiographic evidence of pericardial effusion (n = 8). All affected patients had undergone active fixation (screw-in) lead implantation in the atrial position. The incidence of pericarditis with screw-in atrial leads was 3% compared to 0% in other cases (P < 0.05). CONCLUSIONS: Pericarditis is not uncommon following pacemaker implantation with active fixation atrial leads. Special attention should be paid to identifying pericardial complications following pacemaker implantation, especially when anticoagulant therapy is resumed or initiated. The use of passive fixation leads is likely to reduce the incidence of pericarditis but this issue should be further investigated.

Use of automatic threshold tracking function with non-low polarization leads: risk for algorithm malfunction.

The AutoCapture (AC) function of new pacemakers (PM) from St Jude Medical (SJM) was originally recommended for use with low polarization (LP) ventricular leads only.However, recent reports have encouraged the use of the AC function with various leads, including those lacking a special LP design. The objective of this study was to analyze the reliability and safety of the AC algorithm application with different types of pacing leads. The study group comprised 30 consecutive patients with AC PMs connected to three different types of non-LP leads. Ten patients with SJM LP leads served as the control group. The study protocol included a complete AC function test using four different pulse widths (PW). The pacing threshold was independently assessed by a manual/semiautomatic check. Erratic behavior of polarization measurements with increasing PWs was demonstrated in 43% (n = 13) of the study group. Invalid polarization measurements resulted in erroneous algorithm recommendation to apply AC function in 17% (n = 5) of the study patients. Subsequent AC function activation lead to incorrect threshold determination due to missed noncapture in three patients. AC function should be applied with caution with non-LP leads. "Off label" use of these leads may cause erroneous polarization signal measurements which, in some cases, may result in incorrect pacing threshold determination, rendering a potential risk to dependent patients.

Managing pacemaker safety alerts: experience with three successive models of a single manufacturer.

This report describes the experience of a large pacemaker center during three successive replacement operations due to safety alerts involving three models from the same manufacturer. Between March 1993 and May 1999, 210 patients were implanted with three DDD pacemaker models (Sorin Biomedica, Saluggia, Italy) that were subsequently subject to safety alerts. Pacemaker records were reviewed for complications related to device malfunction, and those secondary to the replacement procedure. Pacemaker malfunction was observed in 16.4% of units despite much lower estimates from the company (range 1-4%). With the exception of one, all units were replaced. Malfunctions were discovered in 7 of 20 pacemakers following an urgent call for follow-up issued as a result of the alert. Twenty units implanted as substitutes for those replaced following the first alert turned out to be subject to the third alert. Significant clinical consequences of malfunction occurred in 5.3% of patients including a near fatal event in one case, while complications related to the replacement procedure occurred in 8.3% of patients, including one fatality. On the issuance of a safety alert, failure rates in a particular center may be higher than published by the manufacturer, and should prompt action by the center to weigh local incidence of device failure against complications of replacement procedures. When device failure mechanism is not entirely clear, particularly in cases of successive model failures, replacement devices from a different manufacturer should be considered.